Bicycle rear sprocket assembly and bicycle drive train

ABSTRACT

A bicycle rear sprocket assembly comprises at least one sprocket. The at least one sprocket includes at least ten internal spline teeth configured to engage with a bicycle hub assembly.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a bicycle rear sprocket assembly and abicycle drive train.

Discussion of the Background

Bicycling is becoming an increasingly more popular form of recreation aswell as a means of transportation. Moreover, bicycling has become a verypopular competitive sport for both amateurs and professionals. Whetherthe bicycle is used for recreation, transportation or competition, thebicycle industry is constantly improving the various components of thebicycle. One bicycle component that has been extensively redesigned is adrive train.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention, a bicyclerear sprocket assembly comprises at least one sprocket. The at least onesprocket includes at least ten internal spline teeth configured toengage with a bicycle hub assembly.

With the bicycle rear sprocket assembly according to the first aspect,the at least ten internal spline teeth reduce a rotational force appliedto each of the at least ten internal spline teeth in comparison with asprocket including nine or less internal spline teeth. This improvesdurability of the at least one sprocket and/or improves a degree offreedom of choosing a material of the at least one sprocket withoutreducing durability of the at least one sprocket.

In accordance with a second aspect of the present invention, the bicyclerear sprocket assembly according to the first aspect is configured sothat a total number of the at least ten internal spline teeth is equalto or larger than 20.

With the bicycle rear sprocket assembly according to the second aspect,the at least twenty internal spline teeth further reduce the rotationalforce applied to each of the at least twenty internal spline teeth incomparison with a sprocket including nine or less internal spline teeth.This further improves durability of the at least one sprocket and/orimproves a degree of freedom of choosing a material of the at least onesprocket without reducing durability of the at least one sprocket.

In accordance with a third aspect of the present invention, the bicyclerear sprocket assembly according to the second aspect is configured sothat the total number of the at least ten internal spline teeth is equalto or larger than 25.

With the bicycle rear sprocket assembly according to the third aspect,the at least twenty-five internal spline teeth further reduce therotational force applied to each of the at least twenty-five internalspline teeth in comparison with a sprocket including nine or lessinternal spline teeth. This further improves durability of the at leastone sprocket and/or improves a degree of freedom of choosing a materialof the at least one sprocket without reducing durability of the at leastone sprocket.

In accordance with a fourth aspect of the present invention, the bicyclerear sprocket assembly according to any one of the first to thirdaspects is configured so that the at least ten internal spline teethhave a first internal pitch angle and a second internal pitch angledifferent from the first internal pitch angle.

With the bicycle rear sprocket assembly according to the fourth aspect,the difference between the first internal pitch angle and the secondinternal pitch angle helps the user to correctly mount the bicycle rearsprocket assembly to the bicycle hub assembly, especially concerning acircumferential position of each sprocket of the bicycle rear sprocketassembly.

In accordance with a fifth aspect of the present invention, the bicyclerear sprocket assembly according to any one of the first to fourthaspects is configured so that at least one of the at least ten internalspline teeth has a first spline shape different from a second splineshape of another of the at least ten internal spline teeth.

With the bicycle rear sprocket assembly according to the fifth aspect,the difference between the first spline shape and the second splineshape helps the user to correctly mount the bicycle rear sprocketassembly to the bicycle hub assembly, especially concerning acircumferential position of each sprocket of the bicycle rear sprocketassembly.

In accordance with a sixth aspect of the present invention, the bicyclerear sprocket assembly according to any one of the first to fifthaspects is configured so that at least one of the at least ten internalspline teeth has a first size different from a second size of another ofthe at least ten internal spline teeth.

With the bicycle rear sprocket assembly according to the sixth aspect,the difference between the first size and the second size helps the userto correctly mount the bicycle rear sprocket assembly to the sprocketsupport body, especially concerning a circumferential position of eachsprocket of the bicycle rear sprocket assembly.

In accordance with a seventh aspect of the present invention, thebicycle rear sprocket assembly according to any one of the first tosixth aspects is configured so that the at least one sprocket includes asmallest sprocket including at least one sprocket tooth. A total numberof the at least one sprocket tooth of the smallest sprocket is equal toor smaller than 10.

With the bicycle rear sprocket assembly according to the seventh aspect,it is possible to widen a gear range of the bicycle rear sprocketassembly on a top gear side.

In accordance with an eighth aspect of the present invention, thebicycle rear sprocket assembly according to any one of the first toseventh aspects is configured so that the at least one sprocket includesa largest sprocket including at least one sprocket tooth. A total numberof the at least one sprocket tooth of the largest sprocket is equal toor larger than 46.

With the bicycle rear sprocket assembly according to the eighth aspect,it is possible to widen the gear range of the bicycle rear sprocketassembly on a low gear side.

In accordance with a ninth aspect of the present invention, the bicyclerear sprocket assembly according to the eighth aspect is configured sothat the total number of the at least one sprocket tooth of the largestsprocket is equal to or larger than 50.

With the bicycle rear sprocket assembly according to the ninth aspect,it is possible to further widen the gear range of the bicycle rearsprocket assembly.

In accordance with a tenth aspect of the present invention, a bicyclerear sprocket assembly comprises at least one sprocket. The at least onesprocket includes a plurality of internal spline teeth configured toengage with a bicycle hub assembly. At least two internal spline teethof the plurality of internal spline teeth are circumferentially arrangedat a first internal pitch angle with respect to a rotational center axisof the bicycle rear sprocket assembly. The first internal pitch angleranges from 10 degrees to 20 degrees.

With the bicycle rear sprocket assembly according to the tenth aspect,the first internal pitch angle reduces a rotational force applied toeach of the at least ten internal spline teeth in comparison with asprocket including nine or less internal spline teeth. This improvesdurability of the at least one sprocket and/or improves a degree offreedom of choosing a material of the at least one sprocket withoutreducing durability of the at least one sprocket.

In accordance with an eleventh aspect of the present invention, thebicycle rear sprocket assembly according to the tenth aspect isconfigured so that the first internal pitch angle ranges from 12 degreesto 15 degrees.

With the bicycle rear sprocket assembly according to the eleventhaspect, the first internal pitch angle further reduces a rotationalforce applied to each of the at least ten internal spline teeth incomparison with a sprocket including nine or less internal spline teeth.This further improves durability of the at least one sprocket and/orimproves a degree of freedom of choosing a material of the at least onesprocket without reducing durability of the at least one sprocket.

In accordance with a twelfth aspect of the present invention, thebicycle rear sprocket assembly according to the eleventh aspect isconfigured so that the first internal pitch angle ranges from 13 degreesto 14 degrees.

With the bicycle rear sprocket assembly according to the twelfth aspect,the first internal pitch angle further reduces a rotational forceapplied to each of the at least ten internal spline teeth in comparisonwith a sprocket including nine or less internal spline teeth. Thisfurther improves durability of the at least one sprocket and/or improvesa degree of freedom of choosing a material of the at least one sprocketwithout reducing durability of the at least one sprocket.

In accordance with a thirteenth aspect of the present invention, thebicycle rear sprocket assembly according to any one of the tenth totwelfth aspects is configured so that at least two internal spline teethof the plurality of internal spline teeth are circumferentially arrangedat a second internal pitch angle with respect to the rotational centeraxis. The second internal pitch angle is different from the firstinternal pitch angle.

With the bicycle rear sprocket assembly according to the thirteenthaspect, the difference between the first internal pitch angle and thesecond internal pitch angle helps the user to correctly mount thebicycle rear sprocket assembly to the bicycle hub assembly, especiallyconcerning a circumferential position of each sprocket of the bicyclerear sprocket assembly.

In accordance with a fourteenth aspect of the present invention, thebicycle rear sprocket assembly according to any one of the tenth tothirteenth aspects is configured so that the at least one sprocketincludes a smallest sprocket including at least one sprocket tooth. Atotal number of the at least one sprocket tooth of the smallest sprocketis equal to or smaller than 10.

With the bicycle rear sprocket assembly according to the fourteenthaspect, it is possible to widen the gear range of the bicycle rearsprocket assembly on a top gear side.

In accordance with a fifteenth aspect of the present invention, thebicycle rear sprocket assembly according to any one of the tenth tofourteenth aspects is configured so that the at least one sprocketincludes a largest sprocket including at least one sprocket tooth. Atotal number of the at least one sprocket tooth of the largest sprocketis equal to or larger than 46.

With the bicycle rear sprocket assembly according to the fifteenthaspect, it is possible to widen the gear range of the bicycle rearsprocket assembly on a low gear side.

In accordance with a sixteenth aspect of the present invention, thebicycle rear sprocket assembly according to the fifteenth aspect isconfigured so that the total number of the at least one sprocket toothof the largest sprocket is equal to or larger than 50.

With the bicycle rear sprocket assembly according to the sixteenthaspect, it is possible to further widen the gear range of the bicyclerear sprocket assembly.

In accordance with a seventeenth aspect of the present invention, abicycle rear sprocket assembly comprises at least one sprocket. The atleast one sprocket includes at least one internal spline toothconfigured to engage with a bicycle hub assembly. The at least oneinternal spline tooth has an internal-spline major diameter equal to orsmaller than 30 mm.

With the bicycle rear sprocket assembly according to the seventeenthaspect, it is possible to manufacture a bicycle rear sprocket with atotal tooth number that is equal to or smaller than 10. Therefore, it ispossible to widen a gear range of the bicycle rear sprocket assembly ona top gear side.

In accordance with an eighteenth aspect of the present invention, thebicycle rear sprocket assembly according to the seventeenth aspect isconfigured so that the internal-spline major diameter is equal to orlarger than 25 mm.

With the bicycle rear sprocket assembly according to the eighteenthaspect, it is possible to ensure strength of the at least one sprocketwith widening the gear range of the bicycle rear sprocket assembly on atop gear side.

In accordance with a nineteenth aspect of the present invention, thebicycle rear sprocket assembly according to the eighteenth aspect isconfigured so that the internal-spline major diameter is equal to orlarger than 29 mm.

With the bicycle rear sprocket assembly according to the nineteenthaspect, it is possible to further ensure strength of the at least onesprocket with widening the gear range of the bicycle rear sprocketassembly on a top gear side.

In accordance with a twentieth aspect of the present invention, thebicycle rear sprocket assembly according to any one of the seventeenthto nineteenth aspects is configured so that the at least one internalspline tooth has an internal-spline minor diameter equal to or smallerthan 28 mm.

With the bicycle rear sprocket assembly according to the twentiethaspect, the internal-spline minor diameter can increase a radial lengthof a driving surface of the at least one internal spline tooth. Thisimproves strength of the at least one sprocket.

In accordance with a twenty-first aspect of the present invention, thebicycle rear sprocket assembly according to any one of the seventeenthto twentieth aspects is configured so that the internal-spline minordiameter is equal to or larger than 25 mm.

With the bicycle rear sprocket assembly according to the twenty-firstaspect, it is possible to ensure strength of the at least one sprocketwith widening the gear range of the bicycle rear sprocket assembly on atop gear side.

In accordance with a twenty-second aspect of the present invention, thebicycle rear sprocket assembly according to the twenty-first aspect isconfigured so that the internal-spline minor diameter is equal to orlarger than 27 mm.

With the bicycle rear sprocket assembly according to the twenty-secondaspect, it is possible to certainly ensure strength of the at least onesprocket with widening the gear range of the bicycle rear sprocketassembly on a top gear side.

In accordance with a twenty-third aspect of the present invention, thebicycle rear sprocket assembly according to any one of the seventeenthto twenty-second aspects is configured so that the at least one internalspline tooth includes a plurality of internal spline teeth including aplurality of internal-spline driving surfaces to receive a drivingrotational force from the bicycle hub assembly during pedaling. Theplurality of internal-spline driving surfaces each includes a radiallyoutermost edge, a radially innermost edge, and a radial length definedfrom the radially outermost edge to the radially innermost edge. A totalof the radial lengths of the plurality of internal-spline drivingsurfaces is equal to or larger than 7 mm.

With the bicycle rear sprocket assembly according to the twenty-thirdaspect, it is possible to increase the radial lengths of the pluralityof internal-spline driving surface. This improves strength of the atleast one sprocket.

In accordance with a twenty-fourth aspect of the present invention, thebicycle rear sprocket assembly according to the twenty-third aspect isconfigured so that the total of the radial lengths is equal to or largerthan 10 mm.

With the bicycle rear sprocket assembly according to the twenty-fourthaspect, it is possible to further increase the radial lengths of theplurality of internal-spline driving surface. This improves strength ofthe at least one sprocket.

In accordance with a twenty-fifth aspect of the present invention, thebicycle rear sprocket assembly according to the twenty-third aspect isconfigured so that the total of the radial lengths is equal to or largerthan 15 mm.

With the bicycle rear sprocket assembly according to the twenty-fifthaspect, it is possible to further increase the radial lengths of theplurality of internal-spline driving surface. This further improvesstrength of the at least one sprocket.

In accordance with a twenty-sixth aspect of the present invention, thebicycle rear sprocket assembly according to any one of the seventeenthto twenty-fifth aspects is configured so that the at least one sprocketincludes a smallest sprocket including at least one sprocket tooth. Atotal number of the at least one sprocket tooth of the smallest sprocketis equal to or smaller than 10.

With the bicycle rear sprocket assembly according to the twenty-sixthaspect, it is possible to widen the gear range of the bicycle rearsprocket assembly on a top gear side.

In accordance with a twenty-seventh aspect of the present invention, thebicycle rear sprocket assembly according to any one of the seventeenthto twenty-sixth aspects is configured so that the at least one sprocketincludes a largest sprocket including at least one sprocket tooth. Atotal number of the at least one sprocket tooth of the largest sprocketis equal to or larger than 46.

With the bicycle rear sprocket assembly according to the twenty-seventhaspect, it is possible to widen the gear range of the bicycle rearsprocket assembly on a low gear side.

In accordance with a twenty-eighth aspect of the present invention, thebicycle rear sprocket assembly according to the twenty-seventh aspect isconfigured so that the total number of the at least one sprocket toothof the largest sprocket is equal to or larger than 50.

With the bicycle rear sprocket assembly according to the twenty-eighthaspect, it is possible to further widen the gear range of the bicyclerear sprocket assembly.

In accordance with a twenty-ninth aspect of the present invention, abicycle rear sprocket assembly comprises at least one sprocket. The atleast one sprocket includes at least one internal spline teethconfigured to engage with a bicycle hub assembly. The at least oneinternal spline tooth comprises an internal-spline driving surface andan internal-spline non-driving surface. The internal-spline drivingsurface has a first internal-spline-surface angle defined between theinternal-spline driving surface and a first radial line extending from arotational center axis of the bicycle rear sprocket assembly to aradially outermost edge of the internal-spline driving surface. Theinternal-spline non-driving surface has a second internal-spline-surfaceangle defined between the internal-spline non-driving surface and asecond radial line extending from the rotational center axis of thebicycle rear sprocket assembly to a radially outermost edge of theinternal-spline non-driving surface. The second internal-spline-surfaceangle is different from the first internal-spline-surface angle.

With the bicycle rear sprocket assembly according to the twenty-ninthaspect, it is possible to save a weight of the at least one sprocketwith ensuring strength of the at least one internal spline teeth of theat least one sprocket.

In accordance with a thirtieth aspect of the present invention, thebicycle rear sprocket assembly according to the twenty-ninth aspect isconfigured so that the first internal-spline-surface angle is smallerthan the second internal-spline-surface angle.

With the bicycle rear sprocket assembly according to the thirtiethaspect, it is possible to effectively save the weight of the at leastone sprocket with ensuring strength of the at least one internal splineteeth of the at least one sprocket.

In accordance with a thirty-first aspect of the present invention, thebicycle rear sprocket assembly according to the twenty-ninth orthirtieth aspect is configured so that the first internal-spline-surfaceangle ranges from 0 degree to 10 degrees.

With the bicycle rear sprocket assembly according to the thirty-firstaspect, the first internal-spline-surface angle ensures strength of theinternal-spline driving surface.

In accordance with a thirty-second aspect of the present invention, thebicycle rear sprocket assembly according to any one of the twenty-ninthto thirty-first aspects is configured so that the secondinternal-spline-surface angle ranges from 0 degree to 60 degrees.

With the bicycle rear sprocket assembly according to the thirty-secondaspect, the second internal-spline-surface angle saves a weight of theat least one sprocket.

In accordance with a thirty-third aspect of the present invention, thebicycle rear sprocket assembly according to any one of the twenty-ninthto thirty-second aspects is configured so that the at least one sprocketincludes a smallest sprocket including at least one sprocket tooth. Atotal number of the at least one sprocket tooth of the smallest sprocketis equal to or smaller than 10.

With the bicycle rear sprocket assembly according to the thirty-thirdaspect, it is possible to widen the gear range of the bicycle rearsprocket assembly on a top gear side.

In accordance with a thirty-fourth aspect of the present invention, thebicycle rear sprocket assembly according to any one of the twenty-ninthto thirty-third aspects is configured so that the at least one sprocketincludes a largest sprocket including at least one sprocket tooth. Atotal number of the at least one sprocket tooth of the largest sprocketis equal to or larger than 46.

With the bicycle rear sprocket assembly according to the thirty-fourthaspect, it is possible to widen the gear range of the bicycle rearsprocket assembly on a low gear side.

In accordance with a thirty-fifth aspect of the present invention, thebicycle rear sprocket assembly according to the thirty-fourth aspect isconfigured so that the total number of the at least one sprocket toothof the largest sprocket is equal to or larger than 50.

With the bicycle rear sprocket assembly according to the thirty-fifthaspect, it is possible to further widen the gear range of the bicyclerear sprocket assembly.

In accordance with a thirty-sixth aspect of the present invention, abicycle drive train comprises the bicycle rear sprocket assemblyaccording to any one of the first to ninth aspects and a bicycle hubassembly. The bicycle hub assembly comprises a sprocket support bodyincluding at least ten external spline teeth configured to engage withthe bicycle rear sprocket assembly. Each of the at least ten externalspline teeth has an external-spline driving surface and anexternal-spline non-driving surface.

With the bicycle drive train according to the thirty-sixth aspect, theat least ten internal spline teeth reduce a rotational force applied toeach of the at least ten internal spline teeth in comparison with asprocket including nine or less internal spline teeth. This improvesdurability of the at least one sprocket and/or improves a degree offreedom of choosing a material of the at least one sprocket withoutreducing durability of the at least one sprocket. Further, the at leastten external spline teeth reduce a rotational force applied to each ofthe at least ten external spline teeth in comparison with a sprocketsupport body including nine or less external spline teeth. This improvesdurability of the sprocket support body and/or improves a degree offreedom of choosing a material of the sprocket support body withoutreducing durability of the sprocket support body.

In accordance with a thirty-seventh aspect of the present invention, abicycle drive train comprises the bicycle rear sprocket assemblyaccording to any one of the tenth to sixteenth aspects and a bicycle hubassembly. The bicycle hub assembly comprises a sprocket support bodyincluding a plurality of external spline teeth configured to engage withthe bicycle rear sprocket assembly. At least two external spline teethof the plurality of external spline teeth are circumferentially arrangedat a first external pitch angle with respect to a rotational center axisof the bicycle hub assembly. The first external pitch angle ranges from10 degrees to 20 degrees.

With the bicycle drive train according to the thirty-seventh aspect, thefirst internal pitch angle reduces a rotational force applied to each ofthe at least ten internal spline teeth in comparison with a sprocketincluding nine or less internal spline teeth. This improves durabilityof the at least one sprocket and/or improves a degree of freedom ofchoosing a material of the at least one sprocket without reducingdurability of the at least one sprocket. Further, the at least tenexternal spline teeth reduce a rotational force applied to each of theat least ten external spline teeth in comparison with a sprocket supportbody including nine or less external spline teeth. This improvesdurability of the sprocket support body and/or improves a degree offreedom of choosing a material of the sprocket support body withoutreducing durability of the sprocket support body.

In accordance with a thirty-eighth aspect of the present invention, abicycle drive train comprises the bicycle rear sprocket assemblyaccording to any one of the seventeenth to twenty-eighth aspects and abicycle hub assembly. The bicycle hub assembly comprises a sprocketsupport body including at least one external spline tooth configured toengage with the bicycle rear sprocket assembly. The at least oneexternal spline tooth has an external-spline major diameter equal to orsmaller than 30 mm.

With the bicycle drive train according to the thirty-eighth aspect, itis possible to manufacture a bicycle rear sprocket with a total toothnumber that is equal to or smaller than 10. Therefore, it is possible towiden a gear range of the bicycle drive train.

In accordance with a thirty-ninth aspect of the present invention, abicycle drive train comprises the bicycle rear sprocket assemblyaccording to any one of the twenty-ninth to thirty-fifth aspects and abicycle hub assembly. The bicycle hub assembly comprises a sprocketsupport body including at least nine external spline teeth configured toengage with the bicycle rear sprocket assembly. At least one of the atleast nine external spline teeth has an asymmetric shape with respect toa circumferential tooth-tip center line. The at least one of the atleast nine external spline teeth comprises an external-spline drivingsurface and an external-spline non-driving surface. The external-splinedriving surface has a first external-spline-surface angle definedbetween the external-spline driving surface and a first radial lineextending from a rotational center axis of the bicycle hub assembly to aradially outermost edge of the external-spline driving surface. Theexternal-spline non-driving surface has a second external-spline-surfaceangle defined between the external-spline non-driving surface and asecond radial line extending from the rotational center axis of thebicycle hub assembly to a radially outermost edge of the external-splinenon-driving surface. The second external-spline-surface angle isdifferent from the first external-spline-surface angle.

With the bicycle drive train according to the thirty-ninth aspect, it ispossible to save a weight of the bicycle drive train with ensuringstrength of the bicycle drive train.

In accordance with a fortieth aspect of the present invention, thebicycle rear sprocket assembly according to any one of the first toninth aspects is configured so that the at least ten internal splineteeth have an internal-spline major diameter equal to or larger than 25mm.

With the bicycle rear sprocket assembly according to the fortiethaspect, it is possible to ensure strength of the at least one sprocket.

In accordance with a forty-first aspect of the present invention, thebicycle rear sprocket assembly according to the fortieth aspect isconfigured so that the internal-spline major diameter is equal to orlarger than 29 mm.

With the bicycle rear sprocket assembly according to the forty-firstaspect, it is possible to further ensure strength of the at least onesprocket.

In accordance with a forty-second aspect of the present invention, thebicycle rear sprocket assembly according to any one of the first toninth, fortieth, and forty-first aspects is configured so that the atleast ten internal spline teeth have an internal-spline minor diameterequal to or larger than 25 mm.

With the bicycle rear sprocket assembly according to the forty-secondaspect, it is possible to ensure strength of the at least one sprocket.

In accordance with a forty-third aspect of the present invention, thebicycle rear sprocket assembly according to the forty-second aspect isconfigured so that the internal-spline minor diameter is equal to orlarger than 27 mm.

With the bicycle rear sprocket assembly according to the forty-thirdaspect, it is possible to certainly ensure strength of the at least onesprocket.

In accordance with a forty-fourth aspect of the present invention, thebicycle rear sprocket assembly according to any one of the first toninth and fortieth to forty-third aspects is configured so that the atleast ten internal spline teeth include a plurality of internal-splinedriving surfaces to receive a driving rotational force from the bicyclehub assembly during pedaling. The plurality of internal-spline drivingsurfaces each includes a radially outermost edge, a radially innermostedge, and a radial length defined from the radially outermost edge tothe radially innermost edge. A total of the radial lengths of theplurality of internal-spline driving surfaces is equal to or larger than7 mm.

With the bicycle rear sprocket assembly according to the forty-fourthaspect, it is possible to increase the radial lengths of the pluralityof internal-spline driving surface. This improves strength of the atleast one sprocket.

In accordance with a forty-fifth aspect of the present invention, thebicycle rear sprocket assembly according to the forty-fourth aspect isconfigured so that the total of the radial lengths is equal to or largerthan 10 mm.

With the bicycle rear sprocket assembly according to the forty-fifthaspect, it is possible to further increase the radial lengths of theplurality of internal-spline driving surface. This improves strength ofthe at least one sprocket.

In accordance with a forty-sixth aspect of the present invention, thebicycle rear sprocket assembly according to the forty-fourth aspect isconfigured so that the total of the radial lengths is equal to or largerthan 15 mm.

With the bicycle rear sprocket assembly according to the forty-sixthaspect, it is possible to further increase the radial lengths of theplurality of internal-spline driving surface. This further improvesstrength of the at least one sprocket.

In accordance with a forty-seventh aspect of the present invention, thebicycle rear sprocket assembly according to any one of the first toninth and fortieth to forty-sixth aspects is configured so that at leasttwo internal spline teeth of the at least ten internal spline teeth arecircumferentially arranged at a first internal pitch angle with respectto a rotational center axis of the bicycle rear sprocket assembly. Thefirst internal pitch angle ranges from 10 degrees to 20 degrees.

With the bicycle drive train according to the forty-seventh aspect, thefirst internal pitch angle reduces a rotational force applied to each ofthe at least ten internal spline teeth in comparison with a sprocketincluding nine or less internal spline teeth. This improves durabilityof the at least one sprocket and/or improves a degree of freedom ofchoosing a material of the at least one sprocket without reducingdurability of the at least one sprocket. Further, the at least tenexternal spline teeth reduce a rotational force applied to each of theat least ten external spline teeth in comparison with a sprocket supportbody including nine or less external spline teeth. This improvesdurability of the sprocket support body and/or improves a degree offreedom of choosing a material of the sprocket support body withoutreducing durability of the sprocket support body.

In accordance with a forty-eighth aspect of the present invention, thebicycle rear sprocket assembly according to the forty-seventh aspect isconfigured so that the first internal pitch angle ranges from 12 degreesto 15 degrees.

With the bicycle rear sprocket assembly according to the forty-eighthaspect, the first internal pitch angle further reduces a rotationalforce applied to each of the at least ten internal spline teeth incomparison with a sprocket including nine or less internal spline teeth.This further improves durability of the at least one sprocket and/orimproves a degree of freedom of choosing a material of the at least onesprocket without reducing durability of the at least one sprocket.

In accordance with a forty-ninth aspect of the present invention, thebicycle rear sprocket assembly according to the forty-seventh aspect isconfigured so that the first internal pitch angle ranges from 13 degreesto 14 degrees.

With the bicycle rear sprocket assembly according to the forty-ninthaspect, the first internal pitch angle further reduces a rotationalforce applied to each of the at least ten internal spline teeth incomparison with a sprocket including nine or less internal spline teeth.This further improves durability of the at least one sprocket and/orimproves a degree of freedom of choosing a material of the at least onesprocket without reducing durability of the at least one sprocket.

In accordance with a fiftieth aspect of the present invention, thebicycle rear sprocket assembly according to the forty-seventh aspect isconfigured so that at least two internal spline teeth of the at leastten internal spline teeth are circumferentially arranged at a secondinternal pitch angle with respect to the rotational center axis. Thesecond internal pitch angle is different from the first internal pitchangle.

With the bicycle rear sprocket assembly according to the fiftiethaspect, the difference between the first internal pitch angle and thesecond internal pitch angle helps the user to correctly mount thebicycle rear sprocket assembly to the bicycle hub assembly, especiallyconcerning a circumferential position of each sprocket of the bicyclerear sprocket assembly.

In accordance with a fifty-first aspect of the present invention, thebicycle rear sprocket assembly according to the any one of first toninth and fortieth to fiftieth aspects is configured so that the atleast ten internal spline teeth comprise an internal-spline drivingsurface and an internal-spline non-driving surface. The internal-splinedriving surface has a first internal-spline-surface angle definedbetween the internal-spline driving surface and a first radial lineextending from a rotational center axis of the bicycle rear sprocketassembly to a radially outermost edge of the internal-spline drivingsurface. The internal-spline non-driving surface has a secondinternal-spline-surface angle defined between the internal-splinenon-driving surface and a second radial line extending from therotational center axis of the bicycle rear sprocket assembly to aradially outermost edge of the internal-spline non-driving surface. Thesecond internal-spline-surface angle is different from the firstinternal-spline-surface angle.

With the bicycle rear sprocket assembly according to the fifty-firstaspect, it is possible to save a weight of the at least one sprocketwith ensuring strength of the at least one internal spline teeth of theat least one sprocket.

In accordance with a fifty-second aspect of the present invention, thebicycle rear sprocket assembly according to the fifty-first aspect isconfigured so that the first internal-spline-surface angle is smallerthan the second internal-spline-surface angle.

With the bicycle rear sprocket assembly according to the fifty-secondaspect, it is possible to effectively save the weight of the at leastone sprocket with ensuring strength of the at least one internal splineteeth of the at least one sprocket.

In accordance with a fifty-third aspect of the present invention, thebicycle rear sprocket assembly according to the fifty-first aspect isconfigured so that the first internal-spline-surface angle ranges from 0degree to 10 degrees.

With the bicycle rear sprocket assembly according to the fifty-thirdaspect, the first internal-spline-surface angle ensures strength of theinternal-spline driving surface.

In accordance with a fifty-fourth aspect of the present invention, thebicycle rear sprocket assembly according to the fifty-first aspect isconfigured so that the second internal-spline-surface angle ranges from0 degree to 60 degrees.

With the bicycle rear sprocket assembly according to the fifty-fourthaspect, the second internal-spline-surface angle saves a weight of theat least one sprocket.

In accordance with a fifty-fifth aspect of the present invention, thebicycle rear sprocket assembly according to any one of the first toninth and fortieth to fifty-fourth aspects further comprises a sprocketsupport to which the at least one sprocket is attached.

In accordance with a fifty-sixth aspect of the present invention, thebicycle rear sprocket assembly according to the fifty-fifth aspect isconfigured so that the sprocket support is made of a non-metallicmaterial including a resin material.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings.

FIG. 1 is a schematic diagram of a bicycle drive train in accordancewith an embodiment.

FIG. 2 is an exploded perspective view of the bicycle drive trainillustrated in FIG. 1.

FIG. 3 is another perspective view of the bicycle drive trainillustrated in FIG. 2.

FIG. 4 is a cross-sectional view of the bicycle drive train taken alongline IV-IV of FIG. 2.

FIG. 5 is an exploded perspective view of a bicycle hub assembly of thebicycle drive train illustrated in FIG. 2.

FIG. 6 is an enlarged cross-sectional view of the bicycle drive trainillustrated in FIG. 4.

FIG. 7 is a perspective view of a sprocket support body of the bicyclehub assembly of the bicycle drive train illustrated in FIG. 2.

FIG. 8 is another perspective view of the sprocket support body of thebicycle hub assembly of the bicycle drive train illustrated in FIG. 2.

FIG. 9 is a side elevational view of the sprocket support bodyillustrated in FIG. 7.

FIG. 10 is a side elevational view of a sprocket support body of thebicycle hub assembly in accordance with a modification.

FIG. 11 is an enlarged cross-sectional view of the sprocket support bodyillustrated in FIG. 7.

FIG. 12 is a cross-sectional view of the sprocket support bodyillustrated in FIG. 7.

FIG. 13 is a perspective view of the bicycle hub assembly of the bicycledrive train illustrated in FIG. 2.

FIG. 14 is a side elevational view of the bicycle hub assembly of thebicycle drive train illustrated in FIG. 2.

FIG. 15 is a rear view of the bicycle hub assembly of the bicycle drivetrain illustrated in FIG. 2.

FIG. 16 is a cross-sectional view of the bicycle hub assembly takenalong line XVI-XVI of FIG. 5.

FIG. 17 is a side elevational view of the bicycle rear sprocket assemblyof the bicycle drive train illustrated in FIG. 2.

FIG. 18 is an exploded perspective view of the bicycle rear sprocketassembly illustrated in FIG. 17.

FIG. 19 is a partial exploded perspective view of the bicycle rearsprocket assembly illustrated in FIG. 17.

FIG. 20 is another partial exploded perspective view of the bicycle rearsprocket assembly illustrated in FIG. 17.

FIG. 21 is another partial exploded perspective view of the bicycle rearsprocket assembly illustrated in FIG. 17.

FIG. 22 is another partial exploded perspective view of the bicycle rearsprocket assembly illustrated in FIG. 17.

FIG. 23 is a perspective cross-sectional view of the bicycle rearsprocket assembly taken along line XXIII-XXIII of FIG. 17.

FIG. 24 is a perspective view of a smallest sprocket of the bicycle rearsprocket assembly illustrated in FIG. 17.

FIG. 25 is another perspective view of the smallest sprocket of thebicycle rear sprocket assembly illustrated in FIG. 17.

FIG. 26 is a side elevational view of the smallest sprocket of thebicycle rear sprocket assembly illustrated in FIG. 17.

FIG. 27 is a side elevational view of a smallest sprocket in accordancewith a modification.

FIG. 28 is an enlarged cross-sectional view of the smallest sprocketillustrated in FIG. 24.

FIG. 29 is a cross-sectional view of the smallest sprocket illustratedin FIG. 24.

FIG. 30 is a cross-sectional view of the sprocket support body and thesmallest sprocket of the bicycle drive train illustrated in FIG. 2.

FIG. 31 is a partial exploded perspective view of the bicycle rearsprocket assembly illustrated in FIG. 17.

FIG. 32 is a perspective view of a sprocket support of the bicycle rearsprocket assembly illustrated in FIG. 17.

DESCRIPTION OF THE EMBODIMENTS

The embodiment(s) will now be described with reference to theaccompanying drawings, wherein like reference numerals designatecorresponding or identical elements throughout the various drawings.

Referring initially to FIG. 1, a bicycle drive train 10 in accordancewith an embodiment comprises a bicycle hub assembly 12 and a bicyclerear sprocket assembly 14. The bicycle hub assembly 12 is secured to abicycle frame BF. The bicycle rear sprocket assembly 14 is mounted onthe bicycle hub assembly 12. A bicycle brake rotor 16 is mounted on thebicycle hub assembly 12.

The bicycle drive train 10 further comprises a crank assembly 18 and abicycle chain 20. The crank assembly 18 includes a crank axle 22, aright crank arm 24, a left crank arm 26, and a front sprocket 27. Theright crank arm 24 and the left crank arm 26 are secured to the crankaxle 22. The front sprocket 27 is secured to at least one of the crankaxle 22 and the right crank arm 24. The bicycle chain 20 is engaged withthe front sprocket 27 and the bicycle rear sprocket assembly 14 totransmit a pedaling force from the front sprocket 27 to the bicycle rearsprocket assembly 14. The crank assembly 18 includes the front sprocket27 as a single sprocket in the illustrated embodiment. However, thecrank assembly 18 can include a plurality of front sprockets. Thebicycle rear sprocket assembly 14 is a rear sprocket assembly. However,structures of the bicycle rear sprocket assembly 14 can be applied tothe front sprocket.

In the present application, the following directional terms “front,”“rear,” “forward,” “rearward,” “left,” “right,” “transverse,” “upward”and “downward” as well as any other similar directional terms refer tothose directions which are determined on the basis of a user (e.g., arider) who sits on a saddle (not shown) of a bicycle with facing ahandlebar (not shown). Accordingly, these terms, as utilized to describethe bicycle drive train 10, the bicycle hub assembly 12, or the bicyclerear sprocket assembly 14, should be interpreted relative to the bicycleequipped with the bicycle drive train 10, the bicycle hub assembly 12,or the bicycle rear sprocket assembly 14 as used in an upright ridingposition on a horizontal surface.

As seen in FIGS. 2 and 3, the bicycle hub assembly 12 and the bicyclerear sprocket assembly 14 have a rotational center axis A1. The bicyclerear sprocket assembly 14 is rotatably supported by the bicycle hubassembly 12 relative to the bicycle frame BF (FIG. 1) about therotational center axis A1. The bicycle rear sprocket assembly 14 isconfigured to be engaged with the bicycle chain 20 to transmit a drivingrotational force F1 between the bicycle chain 20 and the bicycle rearsprocket assembly 14 during pedaling. The bicycle rear sprocket assembly14 is rotated about the rotational center axis A1 in a drivingrotational direction D11 during pedaling. The driving rotationaldirection D11 is defined along a circumferential direction D1 of thebicycle hub assembly 12 or the bicycle rear sprocket assembly 14. Areverse rotational direction D12 is an opposite direction of the drivingrotational direction D11 and is defined along the circumferentialdirection D1.

As seen in FIG. 2, the bicycle hub assembly 12 comprises a sprocketsupport body 28. The bicycle rear sprocket assembly 14 is mounted on thesprocket support body 28 to transmit the driving rotational force F1between the sprocket support body 28 and the bicycle rear sprocketassembly 14. The bicycle hub assembly 12 further comprises a hub axle30. The sprocket support body 28 is rotatably mounted on the hub axle 30about the rotational center axis A1. The bicycle hub assembly 12comprises a lock ring 32. The lock ring 32 is secured to the sprocketsupport body 28 to hold the bicycle rear sprocket assembly 14 relativeto the sprocket support body 28 in an axial direction D2 parallel to therotational center axis A1.

As seen in FIG. 4, the bicycle hub assembly 12 is secured to the bicycleframe BF with a wheel securing structure WS. The hub axle 30 has athrough hole 30A. A securing rod WS1 of the wheel securing structure WSextends through the through hole 30A of the hub axle 30. The hub axle 30includes a first axle end 30B and a second axle end 30C. The hub axle 30extends between the first axle end 30B and the second axle end 30C alongthe rotational center axis A1. The first axle end 30B is provided in afirst recess BF11 of a first frame BF1 of the bicycle frame BF. Thesecond axle end 30C is provided in a second recess BF21 of a secondframe BF2 of the bicycle frame BF. The hub axle 30 is held between thefirst frame BF1 and the second frame BF2 with the wheel securingstructure WS. The wheel securing structure WS includes a structure whichhas been known in the bicycle filed. Thus, it will not be described indetail here for the sake of brevity.

As seen in FIGS. 4 and 5, the bicycle hub assembly 12 further comprisesa brake-rotor support body 34. The brake-rotor support body 34 isrotatably mounted on the hub axle 30 about the rotational center axisA1. The brake-rotor support body 34 is coupled to the bicycle brakerotor 16 (FIG. 1) to transmit a braking rotational force from thebicycle brake rotor 16 to the brake-rotor support body 34.

As seen in FIG. 5, the bicycle hub assembly 12 further comprises a hubbody 36. The hub body 36 is rotatably mounted on the hub axle 30 aboutthe rotational center axis A1. In this embodiment, the sprocket supportbody 28 is a separate member from the hub body 36. The brake-rotorsupport body 34 is integrally provided with the hub body 36 as aone-piece unitary member. However, the sprocket support body 28 can beintegrally provided with the hub body 36. The brake-rotor support body34 can be a separate member from the hub body 36.

The hub body 36 includes a first flange 36A and a second flange 36B.First spokes (not shown) are coupled to the first flange 36A. Secondspokes (not shown) are coupled to the second flange 36B. The secondflange 36B is spaced apart from the first flange 36A in the axialdirection D2. The first flange 36A is provided between the sprocketsupport body 28 and the second flange 36B in the axial direction D2. Thesecond flange 36B is provided between the first flange 36A and thebrake-rotor support body 34 in the axial direction D2.

The lock ring 32 includes an externally threaded part 32A. The sprocketsupport body 28 includes an internally threaded part 28A. The externallythreaded part 32A is threadedly engaged with the internally threadedpart 28A in a state where the lock ring 32 is secured to the sprocketsupport body 28.

As seen in FIG. 6, the bicycle hub assembly 12 further comprises aratchet structure 38. The sprocket support body 28 is operativelycoupled to the hub body 36 with the ratchet structure 38. The ratchetstructure 38 is configured to couple the sprocket support body 28 to thehub body 36 to rotate the sprocket support body 28 along with the hubbody 36 in the driving rotational direction D11 (FIG. 5) duringpedaling. The ratchet structure 38 is configured to allow the sprocketsupport body 28 to rotate relative to the hub body 36 in the reverserotational direction D12 (FIG. 5) during coasting. Accordingly, theratchet structure 38 may be paraphrased into a one-way clutch structure38. The ratchet structure 38 includes structures which have been knownin the bicycle field. Thus, they will not be described in detail herefor the sake of brevity.

The bicycle hub assembly 12 includes a first bearing 39A and a secondbearing 39B. The first bearing 39A and the second bearing 39B areprovided between the sprocket support body 28 and the hub axle 30 torotatably support the sprocket support body 28 relative to the hub axle30 about the rotational center axis A1.

In this embodiment, each of the sprocket support body 28, thebrake-rotor support body 34, and the hub body 36 is made of a metallicmaterial such as aluminum, iron, or titanium. However, at least one ofthe sprocket support body 28, the brake-rotor support body 34, and thehub body 36 can be made of a non-metallic material.

As seen in FIGS. 7 and 8, the sprocket support body 28 includes at leastone external spline tooth 40 configured to engage with the bicycle rearsprocket assembly 14 (FIG. 6). The sprocket support body 28 includes aplurality of external spline teeth 40 configured to engage with thebicycle rear sprocket assembly 14 (FIG. 6). Namely, the at least oneexternal spline tooth 40 includes a plurality of external spline teeth40. The sprocket support body 28 includes at least nine external splineteeth 40 configured to engage with the bicycle rear sprocket assembly 14(FIG. 6). The sprocket support body 28 includes at least ten externalspline teeth 40 configured to engage with the bicycle rear sprocketassembly 14 (FIG. 6).

The sprocket support body 28 includes a base support 41 having a tubularshape. The base support 41 extends along the rotational center axis A1.The external spline tooth 40 extends radially outwardly from the basesupport 41. The sprocket support body 28 includes a larger-diameter part42, a flange 44, and a plurality of helical external spline teeth 46.The larger-diameter part 42 and the flange 44 extend radially outwardlyfrom the base support 41. The larger-diameter part 42 is providedbetween the plurality of external spline teeth 40 and the flange 44 inthe axial direction D2. The larger-diameter part 42 and the flange 44are provided between the plurality of external spline teeth 40 and theplurality of helical external spline teeth 46 in the axial direction D2.As seen in FIG. 6, the bicycle rear sprocket assembly 14 is held betweenthe larger-diameter part 42 and a lock flange 32B of the lock ring 32 inthe axial direction D2. The larger-diameter part 42 may have an interiorcavity so that a drive structure such as a one-way clutch structure canbe contained within the interior cavity. The larger-diameter part 42 canbe omitted from the bicycle hub assembly 12 according to need.

As seen in FIG. 9, a total number of the at least ten external splineteeth 40 is equal to or larger than 20. The total number of the at leastten external spline teeth 40 is equal to or larger than 25. In thisembodiment, the total number of the at least ten external spline teeth40 is 26. However, a total number of the external spline teeth 40 is notlimited to this embodiment and the above ranges.

The at least ten external spline teeth 40 have a first external pitchangle PA11 and a second external pitch angle PA12. At least two externalspline teeth of the plurality of external spline teeth 40 arecircumferentially arranged at the first external pitch angle PA11 withrespect to the rotational center axis A1 of the bicycle hub assembly 12.At least two external spline teeth of the plurality of external splineteeth 40 are circumferentially arranged at the second external pitchangle PA12 with respect to the rotational center axis A1 of the bicyclehub assembly 12. In this embodiment, the second external pitch anglePA12 is different from the first external pitch angle PA11. However, thesecond external pitch angle PA12 can be substantially equal to the firstexternal pitch angle PA11.

In this embodiment, the external spline teeth 40 are arranged at thefirst external pitch angle PA11 in the circumferential direction D1. Twoexternal spline teeth of the external spline teeth 40 are arranged atthe second external pitch angle PA12 in the circumferential directionD1. However, at least two external spline teeth of the external splineteeth 40 can be arranged at another external pitch angle in thecircumferential direction D1.

The first external pitch angle PA11 ranges from 10 degrees to 20degrees. The first external pitch angle PA11 ranges from 12 degrees to15 degrees. The first external pitch angle PA11 ranges from 13 degreesto 14 degrees. In this embodiment, the first external pitch angle PA11is 13.3 degrees. However, the first external pitch angle PA11 is notlimited to this embodiment and the above ranges.

The second external pitch angle PA12 ranges from 5 degrees to 30degrees. In this embodiment, the second external pitch angle PA12 is 26degrees. However, the second external pitch angle PA12 is not limited tothis embodiment and the above range.

The external spline teeth 40 have substantially the same shape as eachother. The external spline teeth 40 have substantially the same splinesize as each other. The external spline teeth 40 have substantially thesame profile as each other when viewed along the rotational center axisA1. As seen in FIG. 10, however, at least one of the at least tenexternal spline teeth 40 can have a first spline shape different from asecond spline shape of another of the at least ten external spline teeth40. At least one of the at least ten external spline teeth 40 can have afirst spline size different from a second spline size of another of theat least ten external spline teeth 40. At least one of the at least tenexternal spline teeth 40 can have a profile different from a profile ofanother of the at least ten external spline teeth 40 when viewed alongthe rotational center axis A1. In FIG. 10, one of the external splineteeth 40 has a spline shape different from a spline shape of the otherteeth of the external spline teeth 40. One of the external spline teeth40 has a spline size different from a spline size of the other teeth ofthe external spline teeth 40. One of the external spline teeth 40 has aprofile different from a profile of the other teeth of the externalspline teeth 40 when viewed along the rotational center axis A1.

As seen in FIG. 11, each of the at least ten external spline teeth 40has an external-spline driving surface 48 and an external-splinenon-driving surface 50. The plurality of external spline teeth 40includes a plurality of external-spline driving surfaces 48 to receivethe driving rotational force F1 from the bicycle rear sprocket assembly14 (FIG. 6) during pedaling. The plurality of external spline teeth 40includes a plurality of external-spline non-driving surfaces 50. Theexternal-spline driving surface 48 is contactable with the bicycle rearsprocket assembly 14 to receive the driving rotational force F1 from thebicycle rear sprocket assembly 14 (FIG. 6) during pedaling. Theexternal-spline driving surface 48 faces in the reverse rotationaldirection D12. The external-spline non-driving surface 50 is provided ona reverse side of the external-spline driving surface 48 in thecircumferential direction D1. The external-spline non-driving surface 50faces in the driving rotational direction D11 not to receive the drivingrotational force F1 from the bicycle rear sprocket assembly 14 duringpedaling.

The at least ten external spline teeth 40 respectively havecircumferential maximum widths MW1. The external spline teeth 40respectively have circumferential maximum widths MW1. Thecircumferential maximum width MW1 is defined as a maximum width toreceive a thrust force F2 applied to the external spline tooth 40. Thecircumferential maximum width MW1 is defined as a straight distancebased on the external-spline driving surface 48.

The plurality of external-spline driving surfaces 48 each includes aradially outermost edge 48A and a radially innermost edge 48B. Theexternal-spline driving surface 48 extends from the radially outermostedge 48A to the radially innermost edge 48B. A first reference circleRC11 is defined on the radially innermost edge 48B and is centered atthe rotational center axis A1. The first reference circle RC11intersects with the external-spline non-driving surface 50 at areference point 50R. The circumferential maximum width MW1 extendsstraight from the radially innermost edge 48B to the reference point 50Rin the circumferential direction D1.

The plurality of external-spline non-driving surfaces 50 each includes aradially outermost edge 50A and a radially innermost edge 50B. Theexternal-spline non-driving surface 50 extends from the radiallyoutermost edge 50A to the radially innermost edge 50B. The referencepoint 50R is provided between the radially outermost edge 50A and theradially innermost edge 50B. However, the reference point 50R cancoincide with the radially innermost edge 50B.

A total of the circumferential maximum widths MW1 is equal to or largerthan 55 mm. The total of the circumferential maximum widths MW1 is equalto or larger than 60 mm. The total of the circumferential maximum widthsMW1 is equal to or larger than 65 mm. In this embodiment, the total ofthe circumferential maximum widths MW1 is 68 mm. However, the total ofthe circumferential maximum widths MW1 is not limited to this embodimentand the above ranges.

As seen in FIG. 12, the at least one external spline tooth 40 has anexternal-spline major diameter DM11. The external-spline major diameterDM11 is equal to or larger than 25 mm. The external-spline majordiameter DM11 is equal to or larger than 29 mm. The external-splinemajor diameter DM11 is equal to or smaller than 30 mm. In thisembodiment, the external-spline major diameter DM11 is 29.6 mm. However,the external-spline major diameter DM11 is not limited to thisembodiment and the above ranges.

The at least one external spline tooth 40 has an external-spline minordiameter DM12. The at least one external spline tooth 40 has anexternal-spline root circle RC12 having the external-spline minordiameter DM12. However, the external-spline root circle RC12 can haveanother diameter different from the external-spline minor diameter DM12.The external-spline minor diameter DM12 is equal to or smaller than 28mm. The external-spline minor diameter DM12 is equal to or larger than25 mm. The external-spline minor diameter DM12 is equal to or largerthan 27 mm. In this embodiment, the external-spline minor diameter DM12is 27.2 mm. However, the external-spline minor diameter DM12 is notlimited to this embodiment and the above ranges.

The larger-diameter part 42 has an outer diameter DM13 larger than theexternal-spline major diameter DM11. The outer diameter DM13 ranges from32 mm to 40 mm. In this embodiment, the outer diameter DM13 is 35 mm.However, the outer diameter DM13 is not limited to this embodiment.

As seen in FIG. 11, the plurality of external-spline driving surfaces 48each includes a radial length RL11 defined from the radially outermostedge 48A to the radially innermost edge 48B. A total of the radiallengths RL11 of the plurality of external-spline driving surfaces 48 isequal to or larger than 7 mm. The total of the radial lengths RL11 isequal to or larger than 10 mm. The total of the radial lengths RL11 isequal to or larger than 15 mm. In this embodiment, the total of theradial lengths RL11 is 19.5 mm. However, the total of the radial lengthsRL11 is not limited to this embodiment.

The plurality of external spline tooth 40 has an additional radiallength RL12. The additional radial lengths RL12 are respectively definedfrom the external-spline root circle RC12 to radially outermost ends 40Aof the plurality of external spline teeth 40. A total of the additionalradial lengths RL12 is equal to or larger than 12 mm. In thisembodiment, the total of the additional radial lengths RL12 is 31.85 mm.However, the total of the additional radial lengths RL12 is not limitedto this embodiment.

At least one of the at least nine external spline teeth 40 has anasymmetric shape with respect to a circumferential tooth-tip center lineCL1. The circumferential tooth-tip center line CL1 is a line connectingthe rotational center axis A1 and a circumferential center point CP1 ofthe radially outermost end 40A of the external spline tooth 40. However,at least one of the external spline teeth 40 can have a symmetric shapewith respect to the circumferential tooth-tip center line CL1. The atleast one of the at least nine external spline teeth 40 comprises theexternal-spline driving surface 48 and the external-spline non-drivingsurface 50.

The external-spline driving surface 48 has a firstexternal-spline-surface angle AG11. The first external-spline-surfaceangle AG11 is defined between the external-spline driving surface 48 anda first radial line L11. The first radial line L11 extends from therotational center axis A1 of the bicycle hub assembly 12 to the radiallyoutermost edge 48A of the external-spline driving surface 48. The firstexternal pitch angle PA11 or the second external pitch angle PA12 isdefined between the adjacent first radial lines L11 (see, e.g., FIG. 9).

The external-spline non-driving surface 50 has a secondexternal-spline-surface angle AG12. The second external-spline-surfaceangle AG12 is defined between the external-spline non-driving surface 50and a second radial line L12. The second radial line L12 extends fromthe rotational center axis A1 of the bicycle hub assembly 12 to theradially outermost edge 50A of the external-spline non-driving surface50.

In this embodiment, the second external-spline-surface angle AG12 isdifferent from the first external-spline-surface angle AG11. The firstexternal-spline-surface angle AG11 is smaller than the secondexternal-spline-surface angle AG12. However, the firstexternal-spline-surface angle AG11 can be equal to or larger than thesecond external-spline-surface angle AG12.

The first external-spline-surface angle AG11 ranges from 0 degree to 10degrees. The second external-spline-surface angle AG12 ranges from 0degree to 60 degrees. In this embodiment, the firstexternal-spline-surface angle AG11 is 5 degrees. The secondexternal-spline-surface angle AG12 is 45 degrees. However, the firstexternal-spline-surface angle AG11 and the secondexternal-spline-surface angle AG12 are not limited to this embodimentand the above ranges.

As seen in FIGS. 13 and 14, the brake-rotor support body 34 includes atleast one additional external spline tooth 52 configured to engage withthe bicycle brake rotor 16 (FIG. 4). In this embodiment, the brake-rotorsupport body 34 includes an additional base support 54 and a pluralityof additional external spline teeth 52. The additional base support 54has a tubular shape and extends from the hub body 36 along therotational center axis A1. The additional external spline tooth 52extends radially outwardly from additional base support 54. A totalnumber of the additional external spline teeth 52 is 52. However, thetotal number of the additional external spline teeth 52 is not limitedto this embodiment.

As seen in FIG. 14, the at least one additional external spline tooth 52has an additional external-spline major diameter DM14. As seen in FIG.15, the additional external-spline major diameter DM14 is larger thanthe external-spline major diameter DM11. The additional external-splinemajor diameter DM14 is substantially equal to the outer diameter DM13 ofthe larger-diameter part 42. However, the additional external-splinemajor diameter DM14 can be equal to or smaller than the external-splinemajor diameter DM11. The additional external-spline major diameter DM14can be different from the outer diameter DM13 of the larger-diameterpart 42.

As seen in FIG. 16, the hub axle 30 includes an axially contact surface30B1 to contact the bicycle frame BF. In this embodiment, the axiallycontact surface 30B1 is contactable with the first frame BF1 of thebicycle frame BF. The first frame BF1 includes a frame contact surfaceBF12. The axially contact surface 30B1 is in contact with the framecontact surface BF12 in a state where the bicycle hub assembly 12 issecured to the bicycle frame BF with the wheel securing structure WS.

A first axial length AL11 is defined from the axially contact surface30B1 to the larger-diameter part 42 in the axial direction D2 withrespect to the rotational center axis A1. The first axial length AL11ranges from 35 mm to 41 mm. The first axial length AL11 can be equal toor larger than 39 mm. The first axial length AL11 can also range from 35mm to 37 mm. In this embodiment, the first axial length AL11 is 36.2 mm.However, the first axial length AL11 is not limited to this embodimentand the above ranges.

The larger-diameter part 42 has an axial end 42A which is the farthestfrom the axially contact surface 30B1 in the axial direction D2. Asecond axial length AL12 is defined from the axially contact surface30B1 to the axial end 42A in the axial direction D2. The second axiallength AL12 ranges from 38 mm to 47 mm. The second axial length AL12 canrange from 44 mm to 45 mm. The second axial length AL12 can also rangefrom 40 mm to 41 mm. In this embodiment, the second axial length AL12 is40.75 mm. However, the second axial length AL12 is not limited to thisembodiment and the above ranges.

An axial length AL13 of the larger-diameter part 42 ranges from 3 mm to6 mm. In this embodiment, the axial length AL13 is 4.55 mm. However, theaxial length AL13 is not limited to this embodiment and the aboveranges.

As seen in FIG. 17, the bicycle rear sprocket assembly 14 comprises atleast one sprocket. The at least one sprocket includes a smallestsprocket SP1 and a largest sprocket SP12. The smallest sprocket SP1 canalso be referred to as a sprocket SP1. The largest sprocket SP12 canalso be referred to as a sprocket SP12. In this embodiment, the at leastone sprocket further includes sprockets SP2 to SP11. The sprocket SP1corresponds to top gear. The sprocket SP12 corresponds to low gear. Atotal number of the sprockets of the bicycle rear sprocket assembly 14is not limited to this embodiment.

The smallest sprocket SP1 includes at least one sprocket tooth SP1B. Atotal number of the at least one sprocket tooth SP1B of the smallestsprocket SP1 is equal to or smaller than 10. In this embodiment, thetotal number of the at least one sprocket tooth SP1B of the smallestsprocket SP1 is 10. However, the total number of the at least onesprocket tooth SP1B of the smallest sprocket SP1 is not limited to thisembodiment and the above range.

The largest sprocket SP12 includes at least one sprocket tooth SP12B. Atotal number of the at least one sprocket tooth SP12B of the largestsprocket SP12 is equal to or larger than 46. The total number of the atleast one sprocket tooth SP12B of the largest sprocket SP12 is equal toor larger than 50. In this embodiment, the total number of the at leastone sprocket tooth SP12B of the largest sprocket SP12 is 51. However,the total number of the at least one sprocket tooth SP12B of the largestsprocket SP12 is not limited to this embodiment and the above ranges.

The sprocket SP2 includes at least one sprocket tooth SP2B. The sprocketSP3 includes at least one sprocket tooth SP3B. The sprocket SP4 includesat least one sprocket tooth SP4B. The sprocket SP5 includes at least onesprocket tooth SPSB. The sprocket SP6 includes at least one sprockettooth SP6B. The sprocket SP7 includes at least one sprocket tooth SP7B.The sprocket SP8 includes at least one sprocket tooth SP8B. The sprocketSP9 includes at least one sprocket tooth SP9B. The sprocket SP10includes at least one sprocket tooth SP10B. The sprocket SP11 includesat least one sprocket tooth SP11B.

A total number of the at least one sprocket tooth SP2B is 12. A totalnumber of the at least one sprocket tooth SP3B is 14. A total number ofthe at least one sprocket tooth SP4B is 16. A total number of the atleast one sprocket tooth SP5B is 18. A total number of the at least onesprocket tooth SP6B is 21. A total number of the at least one sprockettooth SP7B is 24. A total number of the at least one sprocket tooth SP8Bis 28. A total number of the at least one sprocket tooth SP9B is 33. Atotal number of the at least one sprocket tooth SP10B is 39. A totalnumber of the at least one sprocket tooth SP11B is 45. The total numberof the sprocket teeth of each of the sprockets SP2 to SP11 is notlimited to this embodiment.

As seen in FIG. 18, the sprockets SP1 to SP12 are separate members fromeach other. However, at least one of the sprockets SP1 to SP12 can be atleast partly provided integrally with another of the sprockets SP1 toSP12. The bicycle rear sprocket assembly 14 comprises a sprocket support56, a plurality of spacers 58, a first ring 59A, and a second ring 59B.The sprockets SP1 to SP12 are attached to the sprocket support 56 in theillustrated embodiment.

As seen in FIG. 19, the sprocket SP1 includes a sprocket body SP1A andthe plurality of sprocket teeth SP1B. The plurality of sprocket teethSP1B extends radially outwardly from the sprocket body SP1A. Thesprocket SP2 includes a sprocket body SP2A and the plurality of sprocketteeth SP2B. The plurality of sprocket teeth SP2B extends radiallyoutwardly from the sprocket body SP2A. The sprocket SP3 includes asprocket body SP3A and the plurality of sprocket teeth SP3B. Theplurality of sprocket teeth SP3B extends radially outwardly from thesprocket body SP3A. The sprocket SP4 includes a sprocket body SP4A andthe plurality of sprocket teeth SP4B. The plurality of sprocket teethSP4B extends radially outwardly from the sprocket body SP4A. Thesprocket SP5 includes a sprocket body SP5A and the plurality of sprocketteeth SP5B. The plurality of sprocket teeth SP5B extends radiallyoutwardly from the sprocket body SP5A. The first ring 59A is providedbetween the sprockets SP3 and SP4. The second ring 59B is providedbetween the sprockets SP4 and SP5.

As seen in FIG. 20, the sprocket SP6 includes a sprocket body SP6A andthe plurality of sprocket teeth SP6B. The plurality of sprocket teethSP6B extends radially outwardly from the sprocket body SP6A. Thesprocket SP7 includes a sprocket body SP7A and the plurality of sprocketteeth SP7B. The plurality of sprocket teeth SP7B extends radiallyoutwardly from the sprocket body SP7A. The sprocket SP8 includes asprocket body SP8A and the plurality of sprocket teeth SP8B. Theplurality of sprocket teeth SP8B extends radially outwardly from thesprocket body SP8A.

As seen in FIG. 21, the sprocket SP9 includes a sprocket body SP9A andthe plurality of sprocket teeth SP9B. The plurality of sprocket teethSP9B extends radially outwardly from the sprocket body SP9A. Thesprocket SP10 includes a sprocket body SP10A and the plurality ofsprocket teeth SP10B. The plurality of sprocket teeth SP10B extendsradially outwardly from the sprocket body SP10A. The sprocket SP11includes a sprocket body SP11A and the plurality of sprocket teethSP11B. The plurality of sprocket teeth SP11B extends radially outwardlyfrom the sprocket body SP11A. The sprocket SP12 includes a sprocket bodySP12A and the plurality of sprocket teeth SP12B. The plurality ofsprocket teeth SP12B extends radially outwardly from the sprocket bodySP12A.

As seen in FIG. 22, the sprocket support 56 includes a hub engagementpart 60 and a plurality of support arms 62. The plurality of supportarms 62 extends radially outwardly from the hub engagement part 60. Thesupport arm 62 includes first to eighth attachment parts 62A to 62H. Theplurality of spacers 58 includes a plurality of first spacers 58A, aplurality of second spacers 58B, a plurality of third spacers 58C, aplurality of fourth spacers 58D, a plurality of fifth spacers 58E, aplurality of sixth spacers 58F, and a plurality of seventh spacers 58G.

As seen in FIG. 23, the first spacers 58A are provided between thesprockets SP5 and SP6. The second spacers 58B are provided between thesprockets SP6 and SP7. The third spacers 58C are provided between thesprockets SP7 and SP8. The fourth spacers 58D are provided between thesprockets SP8 and SP9. The fifth spacers 58E are provided between thesprockets SP9 and SP10. The sixth spacers 58F are provided between thesprockets SP10 and SP11. The seventh spacers 58G are provided betweenthe sprockets SP11 and SP12.

The sprocket SP6 and the first spacer 58A are attached to the firstattachment part 62A with a bonding structure such as an adhesive agent.The sprocket SP7 and the second spacer 58B are attached to the secondattachment part 62B with a bonding structure such as an adhesive agent.The sprocket SP8 and the third spacer 58C are attached to the thirdattachment part 62C with a bonding structure such as an adhesive agent.The sprocket SP9 and the fourth spacer 58D are attached to the fourthattachment part 62D with a bonding structure such as an adhesive agent.The sprocket SP10 and the fifth spacer 58E are attached to the fifthattachment part 62E with a bonding structure such as an adhesive agent.The sprocket SP11 and the sixth spacer 58F are attached to the sixthattachment part 62F with a bonding structure such as an adhesive agent.The sprocket SP12 and the seventh spacer 58G are attached to the seventhattachment part 62G with a bonding structure such as an adhesive agent.The sprocket SP5 and the second ring 59B are attached to the eighthattachment part 62H with a bonding structure such as an adhesive agent.The hub engagement part 60, the sprockets SP1 to SP4, the first ring59A, and the second ring 59B are held between the larger-diameter part42 and the lock flange 32B of the lock ring 32 in the axial directionD2.

In this embodiment, each of the sprockets SP1 to SP12 is made of ametallic material such as aluminum, iron, or titanium. Each of thesprocket support 56, the first to seventh spacers 58A and to 58G, thefirst ring 59A, and the second ring 59B is made of a non-metallicmaterial such as a resin material. However, at least one of thesprockets SP1 to SP12 can be at least partly made of a non-metallicmaterial. At least one of the sprocket support 56, the first to seventhspacers 58A and to 58G, the first ring 59A, and the second ring 59B canbe at least partly made of a metallic material such as aluminum, iron,or titanium.

The at least one sprocket includes at least one internal spline toothconfigured to engage with the bicycle hub assembly 12. As seen in FIGS.24 and 25, the at least one sprocket includes at least ten internalspline teeth configured to engage with the bicycle hub assembly 12. Theat least one internal spline tooth includes a plurality of internalspline teeth. Thus, the at least one sprocket includes a plurality ofinternal spline teeth configured to engage with the bicycle hub assembly12. In this embodiment, the sprocket SP1 includes at least ten internalspline teeth 64 configured to engage with the bicycle hub assembly 12.In this embodiment, the sprocket SP1 includes the internal spline teeth64 configured to mesh with the external spline teeth 40 of the sprocketsupport body 28 of the bicycle hub assembly 12. The sprocket body SP1Ahas an annular shape. The internal spline teeth 64 extend radiallyinwardly from the sprocket body SP1A.

As seen in FIG. 26, a total number of the at least ten internal splineteeth 64 is equal to or larger than 20. The total number of the at leastten internal spline teeth 64 is equal to or larger than 25. In thisembodiment, the total number of the internal spline teeth 64 is 26.However, the total number of the internal spline teeth 64 is not limitedto this embodiment and the above ranges.

The at least ten internal spline teeth 64 have a first internal pitchangle PA21 and a second internal pitch angle PA22. At least two internalspline teeth of the plurality of internal spline teeth 64 iscircumferentially arranged at a first internal pitch angle PA21 withrespect to the rotational center axis A1 of the bicycle rear sprocketassembly 14. At least two internal spline teeth of the plurality ofinternal spline teeth 64 is circumferentially arranged at a secondinternal pitch angle PA22 with respect to the rotational center axis A1.In this embodiment, the second internal pitch angle PA22 is differentfrom the first internal pitch angle PA21. However, the second internalpitch angle PA22 can be substantially equal to the first internal pitchangle PA21.

In this embodiment, the internal spline teeth 64 are circumferentiallyarranged at the first internal pitch angle PA21 in the circumferentialdirection D1. Two internal spline teeth of the internal spline teeth 64is arranged at the second internal pitch angle PA22 in thecircumferential direction D1. However, at least two internal splineteeth of the internal spline teeth 64 can be arranged at anotherinternal pitch angle in the circumferential direction D1.

The first internal pitch angle PA21 ranges from 10 degrees to 20degrees. The first internal pitch angle PA21 ranges from 12 degrees to15 degrees. The first internal pitch angle PA21 ranges from 13 degreesto 14 degrees. In this embodiment, the first internal pitch angle PA21is 13.3 degrees. However, the first internal pitch angle PA21 is notlimited to this embodiment and the above ranges.

The second internal pitch angle PA22 ranges from 5 degrees to 30degrees. In this embodiment, the second internal pitch angle PA22 is 26degrees. However, the second internal pitch angle PA22 is not limited tothis embodiment and the above range.

At least one of the at least ten internal spline teeth 64 has a firstspline shape different from a second spline shape of another of the atleast ten internal spline teeth 64. At least one of the at least teninternal spline teeth 64 has a first spline size different from a secondspline size of another of the at least ten internal spline teeth 64. Atleast one of the at least ten internal spline teeth 64 has across-sectional shape different from a cross-sectional shape of anotherof the at least ten internal spline teeth 64. As seen in FIG. 27,however, the internal spline teeth 64 can have the same shape as eachother. The internal spline teeth 64 can have the same size as eachother. The internal spline teeth 64 can have the same cross-sectionalshape as each other.

As seen in FIG. 28, the at least one internal spline tooth 64 comprisesan internal-spline driving surface 66 and an internal-spline non-drivingsurface 68. The at least one internal spline tooth 64 includes aplurality of internal spline teeth 64. The plurality of internal splineteeth 64 includes a plurality of internal-spline driving surfaces 66 toreceive the driving rotational force F1 from the bicycle hub assembly 12(FIG. 6) during pedaling. The plurality of internal spline teeth 64includes a plurality of internal-spline non-driving surfaces 68. Theinternal-spline driving surface 66 is contactable with the sprocketsupport body 28 to transmit the driving rotational force F1 from thesprocket SP1 to the sprocket support body 28 during pedaling. Theinternal-spline driving surface 66 faces in the driving rotationaldirection D11. The internal-spline non-driving surface 68 is provided ona reverse side of the internal-spline driving surface 66 in thecircumferential direction D1. The internal-spline non-driving surface 68faces in the reverse rotational direction D12 not to transmit thedriving rotational force F1 from the sprocket SP1 to the sprocketsupport body 28 during pedaling.

The at least ten internal spline teeth 64 respectively havecircumferential maximum widths MW2. The internal spline teeth 64respectively have circumferential maximum widths MW2. Thecircumferential maximum width MW2 is defined as a maximum width toreceive a thrust force F3 applied to the internal spline tooth 64. Thecircumferential maximum width MW2 is defined as a straight distancebased on the internal-spline driving surface 66.

The internal-spline driving surface 66 includes a radially outermostedge 66A and a radially innermost edge 66B. The internal-spline drivingsurface 66 extends from the radially outermost edge 66A to the radiallyinnermost edge 66B. A second reference circle RC21 is defined on theradially outermost edge 66A and is centered at the rotational centeraxis A1. The second reference circle RC21 intersects with theinternal-spline non-driving surface 68 at a reference point 68R. Thecircumferential maximum width MW2 extends straight from the radiallyinnermost edge 66B to the reference point 68R in the circumferentialdirection D1.

The internal-spline non-driving surface 68 includes a radially outermostedge 68A and a radially innermost edge 68B. The internal-splinenon-driving surface 68 extends from the radially outermost edge 68A tothe radially innermost edge 68B. The reference point 68R is providedbetween the radially outermost edge 68A and the radially innermost edge68B.

A total of the circumferential maximum widths MW2 is equal to or largerthan 40 mm. The total of the circumferential maximum widths MW2 is equalto or larger than 45 mm. The total of the circumferential maximum widthsMW2 is equal to or larger than 50 mm. In this embodiment, the total ofthe circumferential maximum widths MW2 is 50.8 mm. However, the total ofthe circumferential maximum widths MW2 is not limited to thisembodiment.

As seen in FIG. 29, the at least one internal spline tooth 64 has aninternal-spline major diameter DM21. The at least one internal splinetooth 64 has an internal-spline root circle RC22 having theinternal-spline major diameter DM21. However, the internal-spline rootcircle RC22 can have another diameter different from the internal-splinemajor diameter DM21. The internal-spline major diameter DM21 equal to orsmaller than 30 mm. The internal-spline major diameter DM21 is equal toor larger than 25 mm. The internal-spline major diameter DM21 is equalto or larger than 29 mm. In this embodiment, the internal-spline majordiameter DM21 is 29.8 mm. However, the internal-spline major diameterDM21 is not limited to this embodiment and the above ranges.

The at least one internal spline tooth 64 has an internal-spline minordiameter DM22 equal to or smaller than 28 mm. The internal-spline minordiameter DM22 is equal to or larger than 25 mm. The internal-splineminor diameter DM22 is equal to or larger than 27 mm. In thisembodiment, the internal-spline minor diameter DM22 is 27.7 mm. However,the internal-spline minor diameter DM22 is not limited to thisembodiment and the above ranges.

As seen in FIG. 28, the plurality of internal-spline driving surface 66includes the radially outermost edge 66A and the radially innermost edge66B. The plurality of internal-spline driving surfaces 66 each includesa radial length RL21 defined from the radially outermost edge 66A to theradially innermost edge 66B. A total of the radial lengths RL21 of theplurality of internal-spline driving surfaces 66 is equal to or largerthan 7 mm. The total of the radial lengths RL21 is equal to or largerthan 10 mm. The total of the radial lengths RL21 is equal to or largerthan 15 mm. In this embodiment, the total of the radial lengths RL21 is19.5 mm. However, the total of the radial lengths RL21 is not limited tothis embodiment and the above ranges.

The plurality of internal spline tooth 64 has an additional radiallength RL22. The additional radial lengths RL22 are respectively definedfrom the internal-spline root circle RC22 to radially innermost ends 64Aof the plurality of internal spline teeth 64. A total of the additionalradial lengths RL22 is equal to or larger than 12 mm. In thisembodiment, the total of the additional radial lengths RL22 is 27.95 mm.However, the total of the additional radial lengths RL22 is not limitedto this embodiment and the above ranges.

At least one of the internal spline tooth 64 has an asymmetric shapewith respect to a circumferential tooth-tip center line CL2. Thecircumferential tooth-tip center line CL2 is a line connecting therotational center axis A1 and a circumferential center point CP2 of theradially innermost end 64A of the internal spline tooth 64. However, atleast one of the internal spline teeth 64 can have a symmetric shapewith respect to the circumferential tooth-tip center line CL2. The atleast one of the internal spline tooth 64 comprises the internal-splinedriving surface 66 and the internal-spline non-driving surface 68.

The internal-spline driving surface 66 has a firstinternal-spline-surface angle AG21. The first internal-spline-surfaceangle AG21 is defined between the internal-spline driving surface 66 anda first radial line L21. The first radial line L21 extends from therotational center axis A1 of the bicycle rear sprocket assembly 14 tothe radially outermost edge 66A of the internal-spline driving surface66. The first internal pitch angle PA21 or the second internal pitchangle PA22 is defined between the adjacent first radial lines L21 (see,e.g., FIG. 26).

The internal-spline non-driving surface 68 has a secondinternal-spline-surface angle AG22. The second internal-spline-surfaceangle AG22 is defined between the internal-spline non-driving surface 68and a second radial line L22. The second radial line L22 extends fromthe rotational center axis A1 of the bicycle rear sprocket assembly 14to the radially outermost edge 68A of the internal-spline non-drivingsurface 68.

In this embodiment, the second internal-spline-surface angle AG22 isdifferent from the first internal-spline-surface angle AG21. The firstinternal-spline-surface angle AG21 is smaller than the secondinternal-spline-surface angle AG22. However, the firstinternal-spline-surface angle AG21 can be equal to or larger than thesecond internal-spline-surface angle AG22.

The first internal-spline-surface angle AG21 ranges from 0 degree to 10degrees. The second internal-spline-surface angle AG22 ranges from 0degree to 60 degrees. In this embodiment, the firstinternal-spline-surface angle AG21 is 5 degrees. The secondinternal-spline-surface angle AG22 is 45 degrees. However, the firstinternal-spline-surface angle AG21 and the secondinternal-spline-surface angle AG22 are not limited to this embodimentand the above ranges.

As seen in FIG. 30, the internal spline teeth 64 mesh with the externalspline teeth 40 to transmit the driving rotational force F1 from thesprocket SP1 to the sprocket support body 28. The internal-splinedriving surface 66 is contactable with the external-spline drivingsurface 48 to transmit the driving rotational force F1 from the sprocketSP1 to the sprocket support body 28. The internal-spline non-drivingsurface 68 is spaced apart from the external-spline non-driving surface50 in a state where the internal-spline driving surface 66 is in contactwith the external-spline driving surface 48.

As seen in FIG. 31, the sprocket SP2 includes a plurality of internalspline teeth 70. The sprocket SP3 includes a plurality of internalspline teeth 72. The sprocket SP4 includes a plurality of internalspline teeth 74. The first ring 59A includes a plurality of internalspline teeth 76. As seen in FIG. 32, the hub engagement part 60 of thesprocket support 56 includes a plurality of internal spline teeth 78.The plurality of internal spline teeth 70 has substantially the samestructure as that of the plurality of internal spline teeth 64. Theplurality of internal spline teeth 72 has substantially the samestructure as that of the plurality of internal spline teeth 64. Theplurality of internal spline teeth 74 has substantially the samestructure as that of the plurality of internal spline teeth 64. Theplurality of internal spline teeth 76 has substantially the samestructure as that of the plurality of internal spline teeth 64. Theplurality of internal spline teeth 78 has substantially the samestructure as that of the plurality of internal spline teeth 64. Thus,they will not be described in detail here for the sake of brevity.

The term “comprising” and its derivatives, as used herein, are intendedto be open ended terms that specify the presence of the stated features,elements, components, groups, integers, and/or steps, but do not excludethe presence of other unstated features, elements, components, groups,integers and/or steps. This concept also applies to words of similarmeaning, for example, the terms “have,” “include” and their derivatives.

The terms “member,” “section,” “portion,” “part,” “element,” “body” and“structure” when used in the singular can have the dual meaning of asingle part or a plurality of parts.

The ordinal numbers such as “first” and “second” recited in the presentapplication are merely identifiers, but do not have any other meanings,for example, a particular order and the like. Moreover, for example, theterm “first element” itself does not imply an existence of “secondelement,” and the term “second element” itself does not imply anexistence of “first element.”

The term “pair of,” as used herein, can encompass the configuration inwhich the pair of elements have different shapes or structures from eachother in addition to the configuration in which the pair of elementshave the same shapes or structures as each other.

The terms “a” (or “an”), “one or more” and “at least one” can be usedinterchangeably herein.

Finally, terms of degree such as “substantially,” “about” and“approximately” as used herein mean a reasonable amount of deviation ofthe modified term such that the end result is not significantly changed.All of numerical values described in the present application can beconstrued as including the terms such as “substantially,” “about” and“approximately.”

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

1. A bicycle rear sprocket assembly comprising: at least one sprocketincluding at least ten internal spline teeth configured to engage with abicycle hub assembly.
 2. The bicycle rear sprocket assembly according toclaim 1, wherein a total number of the at least ten internal splineteeth is equal to or larger than
 20. 3. The bicycle rear sprocketassembly according to claim 2, wherein the total number of the at leastten internal spline teeth is equal to or larger than
 25. 4. The bicyclerear sprocket assembly according to claim 1, wherein the at least teninternal spline teeth have a first internal pitch angle and a secondinternal pitch angle different from the first internal pitch angle. 5.The bicycle rear sprocket assembly according to claim 1, wherein atleast one of the at least ten internal spline teeth has a shapedifferent from a shape of another of the at least ten internal splineteeth.
 6. The bicycle rear sprocket assembly according to claim 1,wherein at least one of the at least ten internal spline teeth has afirst spline size different from a second spline size of another of theat least ten internal spline teeth.
 7. The bicycle rear sprocketassembly according to claim 1, wherein the at least one sprocketincludes a smallest sprocket including at least one sprocket tooth, anda total number of the at least one sprocket tooth of the smallestsprocket is equal to or smaller than
 10. 8. The bicycle rear sprocketassembly according to claim 1, wherein the at least one sprocketincludes a largest sprocket including at least one sprocket tooth, and atotal number of the at least one sprocket tooth of the largest sprocketis equal to or larger than
 46. 9. The bicycle rear sprocket assemblyaccording to claim 8, wherein the total number of the at least onesprocket tooth of the largest sprocket is equal to or larger than 50.10. A bicycle rear sprocket assembly comprising: at least one sprocketincluding a plurality of internal spline teeth configured to engage witha bicycle hub assembly, at least two internal spline teeth of theplurality of internal spline teeth being circumferentially arranged at afirst internal pitch angle with respect to a rotational center axis ofthe bicycle rear sprocket assembly, the first internal pitch angleranging from 10 degrees to 20 degrees.
 11. The bicycle rear sprocketassembly according to claim 10, wherein the first internal pitch angleranges from 12 degrees to 15 degrees.
 12. The bicycle rear sprocketassembly according to claim 11, wherein the first internal pitch angleranges from 13 degrees to 14 degrees.
 13. The bicycle rear sprocketassembly according to claim 10, wherein at least two internal splineteeth of the plurality of internal spline teeth are circumferentiallyarranged at a second internal pitch angle with respect to the rotationalcenter axis, and the second internal pitch angle is different from thefirst internal pitch angle.
 14. The bicycle rear sprocket assemblyaccording to claim 10, wherein the at least one sprocket includes asmallest sprocket including at least one sprocket tooth, and a totalnumber of the at least one sprocket tooth of the smallest sprocket isequal to or smaller than
 10. 15. The bicycle rear sprocket assemblyaccording to claim 10, wherein the at least one sprocket includes alargest sprocket including at least one sprocket tooth, and a totalnumber of the at least one sprocket tooth of the largest sprocket isequal to or larger than
 46. 16. The bicycle rear sprocket assemblyaccording to claim 15, wherein the total number of the at least onesprocket tooth of the largest sprocket is equal to or larger than 50.17. A bicycle rear sprocket assembly comprising: at least one sprocketincluding at least one internal spline tooth configured to engage with abicycle hub assembly, the at least one internal spline tooth having aninternal-spline major diameter equal to or smaller than 30 mm.
 18. Thebicycle rear sprocket assembly according to claim 17, wherein theinternal-spline major diameter is equal to or larger than 25 mm.
 19. Thebicycle rear sprocket assembly according to claim 18, wherein theinternal-spline major diameter is equal to or larger than 29 mm.
 20. Thebicycle rear sprocket assembly according to claim 17, wherein the atleast one internal spline tooth has an internal-spline minor diameterequal to or smaller than 28 mm.
 21. The bicycle rear sprocket assemblyaccording to claim 17, wherein the internal-spline minor diameter isequal to or larger than 25 mm.
 22. The bicycle rear sprocket assemblyaccording to claim 21, wherein the internal-spline minor diameter isequal to or larger than 27 mm.
 23. The bicycle rear sprocket assemblyaccording to claim 17, wherein the at least one internal spline toothincludes a plurality of internal spline teeth including a plurality ofinternal-spline driving surfaces to receive a driving rotational forcefrom the bicycle hub assembly during pedaling, the plurality ofinternal-spline driving surfaces each includes a radially outermostedge, a radially innermost edge, and a radial length defined from theradially outermost edge to the radially innermost edge, and a total ofthe radial lengths of the plurality of internal-spline driving surfacesis equal to or larger than 7 mm.
 24. The bicycle rear sprocket assemblyaccording to claim 23, wherein the total of the radial lengths is equalto or larger than 10 mm.
 25. The bicycle rear sprocket assemblyaccording to claim 23, wherein the total of the radial lengths is equalto or larger than 15 mm.
 26. The bicycle rear sprocket assemblyaccording to claim 17, wherein the at least one sprocket includes asmallest sprocket including at least one sprocket tooth, and a totalnumber of the at least one sprocket tooth of the smallest sprocket isequal to or smaller than
 10. 27. The bicycle rear sprocket assemblyaccording to claim 17, wherein the at least one sprocket includes alargest sprocket including at least one sprocket tooth, and a totalnumber of the at least one sprocket tooth of the largest sprocket isequal to or larger than
 46. 28. The bicycle rear sprocket assemblyaccording to claim 27, wherein the total number of the at least onesprocket tooth of the largest sprocket is equal to or larger than 50.29. A bicycle rear sprocket assembly comprising: at least one sprocketincluding at least one internal spline tooth configured to engage with abicycle hub assembly, the at least one internal spline tooth comprising:an internal-spline driving surface having a firstinternal-spline-surface angle defined between the internal-splinedriving surface and a first radial line extending from a rotationalcenter axis of the bicycle rear sprocket assembly to a radiallyoutermost edge of the internal-spline driving surface; and aninternal-spline non-driving surface having a secondinternal-spline-surface angle defined between the internal-splinenon-driving surface and a second radial line extending from therotational center axis of the bicycle rear sprocket assembly to aradially outermost edge of the internal-spline non-driving surface, thesecond internal-spline-surface angle being different from the firstinternal-spline-surface angle.
 30. The bicycle rear sprocket assemblyaccording to claim 29, wherein the first internal-spline-surface angleis smaller than the second internal-spline-surface angle.
 31. Thebicycle rear sprocket assembly according to claim 29, wherein the firstinternal-spline-surface angle ranges from 0 degree to 10 degrees. 32.The bicycle rear sprocket assembly according to claim 29, wherein thesecond internal-spline-surface angle ranges from 0 degree to 60 degrees.33. The bicycle rear sprocket assembly according to claim 29, whereinthe at least one sprocket includes a smallest sprocket including atleast one sprocket tooth, and a total number of the at least onesprocket tooth of the smallest sprocket is equal to or smaller than 10.34. The bicycle rear sprocket assembly according to claim 29, whereinthe at least one sprocket includes a largest sprocket including at leastone sprocket tooth, and a total number of the at least one sprockettooth of the largest sprocket is equal to or larger than
 46. 35. Thebicycle rear sprocket assembly according to claim 34, wherein the totalnumber of the at least one sprocket tooth of the largest sprocket isequal to or larger than
 50. 36. A bicycle drive train comprising: thebicycle rear sprocket assembly according to claim 1; and a bicycle hubassembly comprising a sprocket support body including at least tenexternal spline teeth configured to engage with the bicycle rearsprocket assembly, each of the at least ten external spline teeth havingan external-spline driving surface and an external-spline non-drivingsurface.
 37. A bicycle drive train comprising: the bicycle rear sprocketassembly according to claim 10; and a bicycle hub assembly comprising asprocket support body including a plurality of external spline teethconfigured to engage with the bicycle rear sprocket assembly, at leasttwo external spline teeth of the plurality of external spline teethbeing circumferentially arranged at a first external pitch angle withrespect to a rotational center axis of the bicycle hub assembly, thefirst external pitch angle ranging from 10 degrees to 20 degrees.
 38. Abicycle drive train comprising: the bicycle rear sprocket assemblyaccording to claim 17; and a bicycle hub assembly comprising a sprocketsupport body including at least one external spline tooth configured toengage with the bicycle rear sprocket assembly, the at least oneexternal spline tooth having an external-spline major diameter equal toor smaller than 30 mm.
 39. A bicycle drive train comprising: the bicyclerear sprocket assembly according to claim 29; and a bicycle hub assemblycomprising a sprocket support body including at least nine externalspline teeth configured to engage with the bicycle rear sprocketassembly, at least one of the at least nine external spline teeth havingan asymmetric shape with respect to a circumferential tooth-tip centerline, the at least one of the at least nine external spline teethcomprising: an external-spline driving surface having a firstexternal-spline-surface angle defined between the external-splinedriving surface and a first radial line extending from a rotationalcenter axis of the bicycle hub assembly to a radially outermost edge ofthe external-spline driving surface; and an external-spline non-drivingsurface having a second external-spline-surface angle defined betweenthe external-spline non-driving surface and a second radial lineextending from the rotational center axis of the bicycle hub assembly toa radially outermost edge of the external-spline non-driving surface,the second external-spline-surface angle being different from the firstexternal-spline-surface angle.
 40. The bicycle rear sprocket assemblyaccording to claim 1, wherein the at least ten internal spline teethhave an internal-spline major diameter equal to or larger than 25 mm.41. The bicycle rear sprocket assembly according to claim 40, whereinthe internal-spline major diameter is equal to or larger than 29 mm. 42.The bicycle rear sprocket assembly according to claim 1, wherein the atleast ten internal spline teeth have an internal-spline major diameterequal to or larger than 25 mm.
 43. The bicycle rear sprocket assemblyaccording to claim 42, wherein the internal-spline major diameter isequal to or larger than 27 mm.
 44. The bicycle rear sprocket assemblyaccording to claim 1, wherein the at least ten internal spline teethinclude a plurality of internal-spline driving surfaces to receive adriving rotational force from the bicycle hub assembly during pedaling,the plurality of internal-spline driving surfaces each includes aradially outermost edge, a radially innermost edge, and a radial lengthdefined from the radially outermost edge to the radially innermost edge,and a total of the radial lengths of the plurality of internal-splinedriving surfaces is equal to or larger than 7 mm.
 45. The bicycle rearsprocket assembly according to claim 44, wherein the total of the radiallengths is equal to or larger than 10 mm.
 46. The bicycle rear sprocketassembly according to claim 44, wherein the total of the radial lengthsis equal to or larger than 15 mm.
 47. The bicycle rear sprocket assemblyaccording to claim 1, wherein at least two internal spline teeth of theat least ten internal spline teeth are circumferentially arranged at afirst internal pitch angle with respect to a rotational center axis ofthe bicycle rear sprocket assembly, and the first internal pitch angleranges from 10 degrees to 20 degrees.
 48. The bicycle rear sprocketassembly according to claim 47, wherein the first internal pitch angleranges from 12 degrees to 15 degrees.
 49. The bicycle rear sprocketassembly according to claim 47, wherein the first internal pitch angleranges from 13 degrees to 14 degrees.
 50. The bicycle rear sprocketassembly according to claim 47, wherein at least two internal splineteeth of the at least ten internal spline teeth are circumferentiallyarranged at a second internal pitch angle with respect to the rotationalcenter axis, and the second internal pitch angle is different from thefirst internal pitch angle.
 51. The bicycle rear sprocket assemblyaccording to claim 1, wherein the at least ten internal spline teethcomprise: an internal-spline driving surface having a firstinternal-spline-surface angle defined between the internal-splinedriving surface and a first radial line extending from a rotationalcenter axis of the bicycle rear sprocket assembly to a radiallyoutermost edge of the internal-spline driving surface; and aninternal-spline non-driving surface having a secondinternal-spline-surface angle defined between the internal-splinenon-driving surface and a second radial line extending from therotational center axis of the bicycle rear sprocket assembly to aradially outermost edge of the internal-spline non-driving surface, thesecond internal-spline-surface angle being different from the firstinternal-spline-surface angle.
 52. The bicycle rear sprocket assemblyaccording to claim 51, wherein the first internal-spline-surface angleis smaller than the second internal-spline-surface angle.
 53. Thebicycle rear sprocket assembly according to claim 51, wherein the firstinternal-spline-surface angle ranges from 0 degree to 10 degrees. 54.The bicycle rear sprocket assembly according to claim 51, wherein thesecond internal-spline-surface angle ranges from 0 degree to 60 degrees.55. The bicycle rear sprocket assembly according to claim 1, furthercomprising a sprocket support to which the at least one sprocket isattached.
 56. The bicycle rear sprocket assembly according to claim 55,wherein the sprocket support is made of a non-metallic materialincluding a resin material.